As engines operate to produce thrust or power, heat is released as a byproduct of that production. Advancements in the power generation and transportation fields have found multiple ways to use this discarded heat for additional purposes. In one such use, heat produced by an engine may be fed into a recovery system.
Some of these recovery systems may include turbogenerators. Turbogenerators are a combination of a turbine and electric generator used for the generation of electric power. Excess heat produced within an engine can then be used to heat a medium which can then flow to power the turbogenerator. Turbogenerators are commonly used in the power generation industry, and are more commonly employed as auxiliary power units for vehicles such as aircraft, transportation trucks, and other types of engine-operated vehicles.
Recovery systems which employ turbogenerators for electric power generation operate under the principles of a thermal cycle. This thermal cycle may be a Rankine cycle. In the Rankine cycle, heat from an engine is supplied externally to a closed loop, which usually uses a working fluid. As the working fluid travels through the closed loop, the working fluid passes through all the components of the recovery system connected to the closed loop. Most of these recovery systems include a tank, a pump, an evaporator, a turbine, and a condenser through which the working fluid flows.
In an ideal recovery system, the pump would continuously feed the working fluid into the turbine for power generation. However, that is not always the case. For a recovery system containing the components listed above to operate correctly, the working fluid must flow at a significant pressure to spin the turbine of the turbogenerator. When the recovery system is in continuous operation, obtaining this pressure is easily achieved. However, during startup of such recovery systems, the initial pressure within the recovery system is low and this pressure value is not met. Therefore, external or additional power sources may be needed to power the pump to build up the working fluid pressure within the recovery system.
For operators of such recovery systems, it would be advantageous to develop a recovery system connected to a turbogenerator in which external or additional power sources are not needed to pressurize the recovery system into a continuously operational state.